Differences in Salivary Habituation to a Taste Stimulus in Bariatric Surgery Candidates and Normal-Weight Controls

Previous studies show that slower habituation to taste stimuli is associated with reduced rates of satiation and greater energy intake. This study compared rates of salivary habituation to gustatory presentations of lemon juice in 34 severely obese bariatric surgery candidates [48.8 +/- 7.9 years, 85% female, body mass index (BMI) = 47.4 +/- 7.5 kg/m(2)] and 18 normal-weight controls (48.4 +/- 9.5 years, 88.9% female, BMI = 22.7 +/- 1.2 kg/m(2)). Parotid saliva was collected from cotton rolls positioned in the oral cavity during two baseline water trials and ten lemon juice trials. Data were condensed into trial blocks, representing mean values for the two baseline water trials and each of five pairs of lemon juice trials (i.e., blocks 1-5). Salivary change across lemon juice trials was calculated by subtracting values for blocks 1 through 5 from baseline. A significant interaction of group (bariatric surgery candidates/normal-weight controls) by blocked trials [F (4, 200) = 3.0; p < 0.05] indicated that the groups differed in their pattern of salivary responding, with bariatric surgery candidates' salivation (grams) failing to decrease significantly over the five blocked trials (-0.47 +/- 0.18, p = 0.12), unlike that of the normal-weight controls (-1.30 +/- 0.25, p < 0.001). These findings suggest that severely obese participants' rate of salivary habituation to a taste stimulus is delayed compared to normal-weight controls. This provides support that satiation in bariatric surgery candidates is impaired, possibly leading to increased energy intake and positive energy balance.